RDoc::Parser

The initialize method takes an RDoc::TopLevel
to fill with parsed content, the name of the file to be parsed, the content
of the file, an RDoc::Options object and an RDoc::Stats object to inform the user of parsed
items. The scan method is then called to parse the file and must return
the RDoc::TopLevel object. By calling super
these items will be set for you.

In order to be used by RDoc the parser needs to
register the file extensions it can parse. Use ::parse_files_matching
to register extensions.

Creates a new Parser storing
top_level, file_name, content,
options and stats in instance variables. In
+@preprocess+ an RDoc::Markup::PreProcess object is
created which allows processing of directives.